Jet pump refrigeration system



p 14, 1954 E. P. NEUMANN El AL JET PUMP REFRIGERATION SYSTEM Filed Feb. 3. 1955 m a as HE E m WM 0 m D.. 2 w 2 E M 0 Dn F afi C Q a 8 O 9 8 2 m m a E f m 4 6 5 5 6 46 .l O 6 4 9 7 3 ,QJI JA] w 7 O p n 5 2%344 r v 7 3 7 040422 889987 TO EVAPORATOR INVENTORS ERNEST F? NEUMANN B FERDINAND LUSTWERK Patented Sept. 14, 1954 JET PUMP REFRIGERATION SYSTEM Ernest P. Neumann and Ferdinand Lustwerk, Lincoln, Mass, assignors to Ultrasonic Corporation, Cambridge, Mass., a corporation of Massachusetts Application February 3, 1953, Serial No. 334,904

6 Claims. 1

This invention relates to refrigeration apparatus and in particular to systems wherein a refrigerant is moved through its cycle by a pressurized motive fluid. In one aspect the present invention comprises an improvement upon the system disclosed in our copending applications for Letters Patent of the United States, Serial No. 235,278, filed July 5, 1951, now Patent No.

2,658,356, November 10, 1953 and Serial No.,

315,888 filed October 21, 1952.

The primary object of the present invention is to improve the efiiciency of an injector employed to feed a boiler supplying pressurized vapor to operate the jet pumps.

An important feature of the invention resides in the combination of a boiler from which pressurized vapor of the motive fluid serves one or more jet pumps which move refrigerant fluid from an evaporator to a condenser, an injector operated by boiler exhaust to feed. the boiler, and a pressure responsive bleeder valve disposed in the throat of the injector, the valve being opened during the starting period to prevent flooding.

To start an injector it is desirable to dump part of the initial flow, since the initial operation is accompanied by a surplusage of vapors of the motive fluid which build up to relatively high pressure in the system and impede the generation of the desired flow of liquid. We have found that by disposing a valve controlled outlet in the throat of the injector, the system may be bled during the high pressure starting phase of operations and antomatically restored to normal when the pressure falls after the flow of liquid commences.

These and other objects and features of the 4 invention will be more readily understood from the following detailed description of a preferred embodiment thereof selected for purposes of illustration and shown in the accompanying drawing, in which the figure is a diagrammatic view partly in cross-section through the boiler, injector, and jet pump assembly.

In advance of a discussion of the details of the embodiments herein shown it will be helpful first to consider the general organization of the system. There is provided a conventional evaporator of standard construction (not shown) and a boiler [2 of elongated tubular form. The boiler l2 serves a pair of jet pumps contained in a housing I 4 and connected in series by a pipe l6 having cooling fins l8 secured thereto. Refrigerant gas from the evaporator is pumped and compressed by the jet pumps working in tandem, the eiiiuent therefrom being thereafter passed through a condenser 22 in which it yields heat and liquefies.

From the condenser 22 the liquid refrigerant, together with the motive fluid injected from the boiler l2, passes through a tube 24 and into a gravity separating chamber 26. As shown the connections are established for operation with a heavier refrigerant and a lighter motive fluid. Hence the former collects at the bottom of the separator 26 and is drawn off through a pipe 28 and returned to the evaporator through a conventional expansion valve (not shown).

The lighter motive fluid fills the upper portion of the separator and is drawn off through an injector contained in a housing 30 and thereby pumped back to the boiler I2. The injector in the housing 30 is powered by vapor exhausted from the boiler l2 and conducted to the injector through an external tube 18. Heat for the boiler is supplied by electricity through a resistance element in the form of nichrome windings served by a supply line 32.

With the foregoing general remarks in mind the details of the boiler and jet pump assembly can more easily be understood. As shown the boiler comprises an outer tube or shell l2 within which and concentrically arranged is a tube 40 around which is wrapped a spiral of nichrome wire 39, the latter being protected in turn by a casing 4|. There is thus formed an elongated annular chamber 42 lying between the casing 4| and the shell 12. At the bottom of the tube 40 there is disposed a ball check valve 44 serving to prevent the draining of liquid from the bottom of the boiler. At the top of the tube 40 there is a second ball check valve working against a spring 52 set in a socket formed in a plug 48 serving to close the top of the shell l2. Adjacent the upper end of the boiler shell i2 is an outlet 54 which is coupled to an injector nozzle 56 having its inner passage so shaped that vapor leaving the boiler shell I2 first encounters a converging wall portion in which the pressure of the vapor is raised and then a diverging or diffuser portion which discharges into the housing l4. Refrigerant gas is admitted into the housing l4 through a pipe 58 connected into the exhaust end of the evaporator. One end of the tube i6 is enlarged as shown at 60 and projected within the housing [4 opposite the injector nozzle 56.

The rush of vapor through the nozzle 55 and into the tube 60 carries with it refrigerant gas entering the housing I4 through the pipe 58 and the refrigerant gas thus entrained is compressed to a preliminary extent in the tube H3; another result, of course, is to create suction in the line 58 leading from the evaporator. Disposed below the outlet 54 is a second outlet 62 receiving one end of a bellows connection 64 which is coupled at its outer end to the housing l4 and to a second and smaller jet nozzle 66. The condenser tube 22 has an enlarged head projected into the housing I4 opposite the difiuser end of the nozzle 66, the result being that partially compressed refrigerant together with motive fluid introduced into the tube i6 is discharged into the housing l4 and then entrained in the rush of vapor through the nozzle 66 and dispatched through the condenser tube 22 where the refrigerant will condense to a liquid as it passes through the condenser 22. As a matter of fact, most of the motive fiuid will be condensed by the time it reaches the bottom of the housing [4, and we provide a trapped drain 68 leading from the bottom of the housing M to the top of the separator 26, the drain 68 having a U-shaped loop portion effective to provide a head of pressure sufficient to prevent liquid in the separator from blowing back into the housing 14 through the drain 68.

Adjacent the upper end of the separator there is provided an outlet pipe It leading through a ball check valve 'H to a housing 1-30 in which is contained a jet nozzle 12 disposed opposite an injector nozzle 80 leading to a vertical pipe 46 which is connected into the bottom of the tube 40 below the ball check valve 44. Adjacent the bottom of the boiler shell I2 there is provided an annular housing enclosing a conduit 16 leading to a tube l8 which in turn terminates in the nozzle 12.

The injector feeding the boiler is designated in general by the reference character 80 and includes a throat portion 82, a restricted orifice portion 84 and a delivery tube 74. Adjacent the orifice 84 the body of the nozzle 88 is provided internally with a circular canal or passage 90 having an outlet 92 at one side and communicating with the throat 82 of the nozzle through an inclined annular port 94. The outlet 92 is connected to a ball check valve 96 which in turn is connected to a conduit 98 leading to the condenser tube 22.

The disposition of the port 94 is extremely critical and depends upon the dimensions of the jet nozzle 72, the throat 82, the orifice 84 and the delivery tube 14. These dimensions in turn depend upon the nature of the liquids and gases employed, the operating pressures and other variables. In general it can be said that the port 94 must be disposed at a location in the throat 82 Where the diameter is at least double that of the orifice of the jet nozzle 12. In view of the complexity and subtlety of the effective variables and the extent of the difficult calculations required, we have found that the best procedure is to determine experimentally for a given size of installation of optimum position of the port 94.

When the apparatus is placed in operation and heat supplied to the boiler, the vaporization of the liquid therein eventually causes the ball 50 to lift and exhaust vapor then reaches the jet nozzle 12. At first the suction in the tube 10 is low, and the pressure in the throat 82 is high, the result being that no fluid is drawn from the separator 26. Consequently there is present an excess of vaporized motive fluid, but the excess is bled through the port 94 and into the canal 90 and outlet 92, the pressure being great enough to open the check valve 96 and discharge the vapor into the condenser tube.

As the operation continues, the pressure in the throat 82 decreases, the injector reaches a state of efficient operation and suction is created in the tube 10. Consequently the ball check H is lifted and fluid is drawn from the separator and injected through the tube 46 into the boiler. The decrease in pressure within the throat 82 causes the check valve 96 to close, shutting off the outlet 92, and the injector operates in normal fashion.

Having thus disclosed our invention what we claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigeration system including a boiler, a condenser, a jet pump connected to said boiler and to said condenser, the combination of an injector having a throat portion, an orifice and a delivery tube, said injector being connected to pump liquid from said condenser into said boiler, an outlet port disposed in the throat portion of said injector, and a valve controlled conduit connecting said outlet port to said condenser.

2. In a refrigeration system including a boiler, a condenser, a jet pump connected to said boiler and to said condenser, the combination of an injector having a throat portion, an orifice and a delivery tube, said injector being connected to pump liquid from said condenser into said boiler, an annular outlet port disposed in the throat portion of said injector, and a valve controlled conduit connecting said outlet port to said condenser.

3. In a refrigeration system including a. boiler, a condenser, a jet pump connected to said boiler and to said condenser, the combination of an injector having a throat portion, an orifice and a delivery tube, said injector being connected to pump liquid from said condenser into said boiler, an annular outlet port disposed in the throat portion of said injector, a conduit connecting said outlet port to said condenser, and a check valve disposed in said conduit preventing flow from said condenser to said outlet port.

4. In a refrigeration system including a boiler, a condenser, a, jet pump connected to said boiler and to said condenser, and a separator connected to said condenser; an injector having a throat portion and connected to pump liquid from said separator to said boiler, a check valve disposed in the connection between said injector and separator, an annular port disposed in the throat portion of said injector, a conduit connecting said port to said condenser, and a ball check valve disposed in said conduit preventing flow from said condenser to said port.

5. In a refrigeration system including a boiler, a condenser, a jet pump connected to said boiler and to said condenser, and a separator connected to said condenser; an injector having a throat portion and connected to pump liquid from said separator to said boiler, a check valve d s d i th nection between said injector and separator, a circular canal disposed in said injector, an annular port connecting the throat portion of said injector to said canal, and a conduit connecting said port to said condenser.

6. In a refrigeration system including a boiler, a condenser, a jet pump connected to said boiler and to said condenser, and a separator connected to said condenser; an injector having a throat portion and connected to pump liquid from said separator to said boiler, a check valve 10 disposed in the connection between said injector and separator, a circular canal disposed in said injector, an annular port-connecting the throat 5 said throat.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,975,704 Wilkes Oct. 2, 1934 2,637,174 Austin May 5, 1953 

